Write the surety's handwritten mention (guarantor, no login)

A guarantor (caution) types, in their own words, the mention required by article 2297 of the French Civil Code. This must happen before POST /public/guest-signature/{token}/sign: without a mention written by the surety themselves, the undertaking is void. The deed is regenerated with their characters and only then can be signed.

The text is compared to the expected mention by the domain, which owns the tolerance on accents and punctuation. Nothing is normalised client-side: the proof has to stay literal, so send the keystrokes as typed.

Typing evidence

The optional mode_saisie, evenements_saisie and duree_saisie_ms fields record how the text arrived in the field. Case law accepts a keyboard-entered mention on the basis that the surety actually typed it, and these fields are what lets you say so. They are reported by the client, so they are never probative on their own, but omitting mode_saisie records the undertaking with an unknown input mode, and it will never be assumed to have been typed.

Why a rejection is 422 and not 400

A non-conforming mention is a well-formed request; what is not constituted is the undertaking. On MENTION_NON_CONFORME the response carries mention_attendue so the surety can copy it without guessing what they missed.